This invention pertains to refrigeration systems, and more particularly to a discharge valve and baffle assembly for controlling the flow of high pressure gaseous refrigerant from a compressor to a condenser.
Most refrigeration systems include with the evaporator and condenser a single compressor for drawing low pressure gaseous refrigerant from the evaporator and compressing it to a higher pressure and then delivering the high pressure gaseous refrigerant to the condenser. During the operation of a refrigeration system, several undesirable transient conditions can occur. For example, in a centrifugal compressor one of these is a surge condition wherein the flow of refrigerant reverses, thereby decreasing efficiency of the refrigeration system and causing potential harm to various components therein.
Another undesirable transient condition with centrifugal compressors occur during startup of a multi-compressor system after it has been temporarily shut down for lack of a refrigerant load to be satisfied. At times, an established head exists during startup of one of the compressors, and this established head causes excessive torque requirements for starting the compressor. For example, in a centrifugal compressor, startup against an established head could prevent the compressor from coming to full speed.
Yet another undesired transient condition that exists is primarily associated with refrigeration systems having at least two compressors. The transient condition here is when one compressor is operating and the other is shut down. The operating compressor can cause backflow of refrigerant towards or through the shut down compressor. This condition can also exist in refrigeration systems having only a single compressor.
Current attempts to prevent the occurrence of these undesirable transient conditions include placing a discharge check valve between the compressor and condenser that attempts to eliminate effects of an established head on startup of a compressor, and to prevent backflow of refrigerant through a compressor.
Several disadvantages exist with some of these prior art discharge check valves. One such disadvantage is that the valve can violently slam between the open and closed positions in cyclical fashion during surge conditions. This tends to cause premature failure of the valve, and also creates undesirable noise during operation.
Another disadvantage with some of these current check valves is that they create a large and undesired pressure drop between the compressor and condenser due to the valve acting as an obstruction to refrigerant flow. The circuitous path the refrigerant must follow to flow through the valve creates the large pressure drop.
Another problem or failure of some prior art check valves is that they do not provide a baffle feature for the refrigerant flowing from the compressor to the condenser. This requires a separate baffle member to be constructed and disposed in the condenser to direct the incoming flow of high pressure gaseous refrigerant among, for example, the heat exchanger tubes in a shell and tube condenser.